Edith Arangoitia, 46 (who accompanied her elderly mother), is vaccinated with the Pfizer-BioNTech Covid-19 vaccine by Dr. Galen Harnden at The Chelsea Collaborative, Massachusetts, on February 16, 2021.
Joseph Precious | AFP | Getty Images
Dr. Anthony Fauci, the White House chief medical adviser, said Monday that Americans should continue to take two doses of the Pfizer and Moderna Covid-19 vaccines, despite a recent U.S. study that showed the shots are highly effective after a single dose.
A study by the Centers for Disease Control and Prevention published last week found that a single dose of Cfid-19 vaccine from Pfizer or Moderna was 80% effective in preventing coronavirus infections among health care workers and other essential workers. . Two doses are better than one, federal health officials said, adding that vaccine effectiveness increased to 90 percent two weeks after the second dose.
Although the 80% figure was great news, Fauci said Monday that he is still concerned about the duration of protection after a single dose, especially with the emergence of highly contagious variants that have demonstrated the ability to evade vaccine protection.
“When you look at the level of protection after a dose, you can say it’s 80%, but it’s 80%,” Fauci said during a briefing on the White House pandemic. “When you leave it at a dose, the question is how hard?”
Highly infectious Covid-19 variants that have shown some resistance to vaccines also pose a challenge, Fauci said. “You’re in a faint area if you don’t have the full impact” of two doses, he said.
Fauci’s comments come as some health experts and public health officials argue that the United States should prioritize administering only one dose of vaccines to Americans before switching to second doses, accelerating the pace of vaccinations in the whole country.
Unlike the Johnson & Johnson vaccine, which requires a dose, the Pfizer and Moderna vaccines require two shots between three and four weeks apart. In the UK, health officials decided to extend the time between the first and second dose to 12 weeks in order to speed up vaccinations.
Fauci has repeatedly said in recent months that the U.S. should comply with the two-dose regimen.
Dr. Paul Offit, a voting member of the FDA-related Vaccine and Biological Products Advisory Committee that reviewed the Pfizer and Moderna vaccine for emergency use authorization, told CNBC last week that studies have shown that immunity appears to be more “durable” after the second dose, meaning protection can last longer.
The two-dose vaccination regimen also produces ten times the amount of neutralizing antibodies, which play an important role in fighting the virus, from the first to the second dose, Offit told CNBC.
Second, and most importantly, the scientists also detected so-called T cells after the second dose, another important part of the immune response that usually provides a more lasting immunity, he said.
Fauci said Monday that he “respects” the arguments for a single-dose strategy, but added that the U.S. currently has enough doses to provide the first and second doses for Americans. “While we always keep an open mind, we consider the route we take to be the best route,” he said.